Last year, she gave birth to her second child. Last month, she was diagnosed with leukemia. When I entered her room early one morning, she looked despondent. “Please know you’ve got a great team caring for you,” I told her. “We’ll fight this together.”

She looked pensively out the window as the sun began to rise. “Yes,” she finally said. “I’m a fighter.”

As I left the room, I couldn’t help thinking of another “fighter”—my aunt, who passed away from lymphoma nearly a decade earlier. I’ve long wondered whether that word—fighter—and the other military language used to help her conceptualize her disease did more harm than good. Did she, on some level, feel she lost the battle because she didn’t fight hard enough? Might she have suffered less at the end if she hadn’t felt compelled to try one more drug, determined to soldier on?

The words we choose to describe illness are powerful. They carry weight and valence, creating the milieu in which goals of care are discussed and treatment plans designed. In medicine, the use of metaphor is pervasive. Antibiotics clog up bacterial machinery by disrupting the supply chain. Diabetes coats red blood cells with sugar until they’re little glazed donuts. Life with chronic disease is a marathon, not a sprint, with bumps on the road and frequent detours.

One study, from 2010, found that physicians use metaphors in almost two-thirds of their conversations with patients who have serious illnesses. Physicians who used more metaphors were seen as better communicators. Patients reported less trouble understanding them, and felt as though their doctor made sure they understood their conditions.

Metaphors are a fundamental mechanism through which our minds conceptualize the world around us, especially in the face of complexity. But evidence suggests they do more than explain similarities—they can invent them where they don’t exist, and blur the lines between the literal and the figurative.

One such example comes from research conducted by Lawrence Williams and John Baugh, suggesting that people often confuse physical warmth with social warmth. In their study, a researcher asked participants to briefly hold either a hot or iced coffee on their way to the experimental room, seemingly before the experiment had begun. Later participants read an ambiguous description of an anonymous individual. Those who had held the hot coffee were more likely to rate that individual as having “warmer” personality traits like generosity and compassion. In another study, participants who held the warm coffee were more likely to choose to give a gift to a friend than to take it for themselves.

Other work done by Chen-Bo Zhong and Katie Liljenquist explores the Macbeth Effect, in which suggestions of moral impurity stimulate a desire to cleanse oneself physically in an attempt to wash away one’s sins. In a series of studies, the authors found that participants prompted to think of their own or others’ moral indiscretions were more likely to rate cleaning products as more desirable than other products, and were twice as likely to choose an antiseptic wipe over a pencil when offered a gift for participating. Even more interesting is participants’ unspoken perception that washing their hands restores their moral integrity. Those who were reminded of their unethical behavior and had the opportunity to clean their hands after were almost 50 percent less likely to help out with another study, suggesting that subconsciously they felt physical cleansing had absolved them of previous unethical behavior.

These unconscious processes seem to play out even when we analyze complicated, cerebral issues. In another study, researchers asked people to help solve a city’s crime problem, which was described either as “virus infecting a city” or a “wild beast preying on a city.” People who got the “virus” frame were far more likely to propose solutions involving social reform to address root causes like poverty and lack of education, while those receiving the “beast” frame were more likely to propose solutions involving catching criminals and enforcing laws more strictly. Almost none of the subjects identified the metaphorical frame as being important to their decision-making process, instead crediting hard data like statistics and facts. But the magnitude of the metaphor effect was larger than pre-existing differences of opinion between liberals and conservatives.

If thinking of a virus affects how we address crime and punishment, might thinking of conflict and combat—as I encouraged my patient to do—affect how we address a virus?

Military metaphors are among the oldest in medicine and they remain among the most common. Long before Louis Pasteur deployed imagery of invaders to explain germ theory in the 1860s, John Donne ruminated on the “miserable condition of man,” describing illness as a “siege…a rebellious heat, [that] will blow up the heart, like a Myne” and a “Canon [that] batters all, overthrowes all, demolishes all…destroyes us in an instant.”

Thomas Sydenham, the most famous physician of the 17th century, known as the English Hippocrates, is often credited with introducing military language into Western medical parlance. Writing in the mid-17th century, Sydenham declares that a “murderous array of disease has to be fought against, and the battle is not a battle for the sluggard.” His aim is to investigate illness, comprehend its character, and “proceed straight ahead, and in full confidence, towards its annihilation.” Describing his approach to venereal disease, he continues: “I attack the enemy within by means of cathartics and refrigerants.”

Over the centuries, we’ve internalized these military metaphors, so much so that we often may not recognize how they influence us. Even today, we “monitor for insidious disease,” “destroy rogue cells,” “search for silver bullets,” and “use all weapons at our disposal.” But when the purpose of treatment is not recovering from a cold, but living with cancer, should the military metaphor be retired?

Many patients may prefer not to view illness as a battle or conflict. Indeed, it seems strange that the language of healing remains so interwoven with the language of warfare, especially in the era of chronic disease, when many conditions are controlled and managed, not eradicated or annihilated.

By describing a treatment as a battle and a patient as a combatant, we set an inherently adversarial tone, and dichotomize outcomes into victory and defeat. Changes in medication regimens become setbacks or retreats, and transitions to palliative care mark the end of struggle, the battle lost. We subtly place an unfair burden on patient and doctor, when in reality, even the most courageous soldier guided by the most effective strategy is too often unsuccessful against an aggressive invader with nothing to lose.

Some have suggested that viewing cancer as a fight can lead to maladaptive coping mechanisms and encourage emotional suppression. In 1970, Polish physician Zbigniew Lipowski introduced a framework for characterizing the meaning that patients ascribe to their illnesses. These categories include viewing illness as a challenge, value, enemy, or loss, among others. Since then, studies that have interviewed cancer patients around the time of diagnosis and followed them for years after have found that patients who view their disease as an “enemy” tend to have higher levels of depression and anxiety, and poorer quality of life than those who ascribe a more positive meaning. They also tend to report higher pain scores and lower coping scores. These findings have been replicated in other conditions, including rheumatoid arthritis and sarcoidosis. More recent work has found that patients encouraged to “fight” may feel that they have to suppress their emotional distress and maintain a positive attitude to avoid upsetting family members—and clinicians.

And yet, it’s almost instinctive to think of disease, especially cancer, in the context of a battle. As Gary Reisfield and George Wilson at the University of Florida write, “there exists a seemingly perfect metaphoric correspondence: there is an enemy (the cancer), a commander (the physician), a combatant (the patient), allies (the healthcare team), and formidable weaponry (including chemical, biological, and nuclear weapons).”

Indeed, for many patients, thinking of their treatment course as a fight or battle may be helpful, an important part of their journey, invoking ideals of courage, resilience, and determination. This may be especially true when the “fight” is understood as a challenge, an opportunity for personal growth, rather than an enemy to be defeated. And since 1971, when President Nixon declared a “War on Cancer,” this imagery has been effective for inspiring the fervor and funds necessary for great advances in cancer care and research.

Ultimately, any metaphor—military or otherwise—is not inherently good or bad. Rather, the utility of each depends on a patient’s culture, values, experiences, and preferences. Metaphors allow doctors to develop a common language with patients, and offer patients an avenue to express their emotions and exert agency over their conditions. Just as patients are the deciders of the character and duration of their treatment, they deserve to be the keepers of the lens through which they view their illness. As writer Anatole Broyard put it, “Metaphors may be as necessary to illness as they are to literature, as comforting to the patient as his own bathrobe and slippers.”

I moved on to a new medical service a few days after that morning I deemed my patient a fighter. I don’t know how she ultimately fared, or whether she came to see her illness as a battle, journey, marathon, rollercoaster, chess match—or none of the above. But I do know it wasn’t my decision to make.

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Dhruv Khullar, M.D., is a resident physician at the Massachusetts General Hospital and Harvard Medical School. His work has also appeared in the New England Journal of Medicine, The New York Times, and Politico.